To implement conditional statistics in the count () function, use the SUM function to replace

To implement conditional statistics in the count () function, use the SUM function to replace the count () function and use the SUM function to implement conditional statistics, you can use the case when statement or Decode function to convert the data to 0 or 1, as shown in the following example:

SELECT s. user_id, SUM (case (m. is_success) when 1 then 1 else 0 end), SUM (case when m. read_time is null then 0 else 1 end), COUNT (*) from doc_score s, mail_send_log m where s. user_id in (6, 7, 8, 9) and s. status = 1 and m.doc _ id = s.doc _ id group by s. user_id;